Cellulase enzymes have been used in detergent compositions for many years now for their known benefits of depilling, softness and colour care. However, the use of most of cellulases has been limited because of the negative impact that cellulase may have on the tensile strength of the fabrics' fibers by hydrolysing crystalline cellulose. Recently, cellulases with a high specificity towards amorphous cellulose have been developed to exploit the cleaning potential of cellulases while avoiding the negative tensile strength loss. Especially alkaline endo-glucanases have been developed to suit better the use in alkaline detergent conditions.
For example, Novozymes in WO02/099091 discloses a novel enzyme exhibiting endo-beta-glucanase activity (EC 3.2.1.4) endogenous to the strain Bacillus sp., DSM 12648; for use in detergent and textile applications. Novozymes further describes in WO04/053039 detergent compositions comprising an anti-redeposition endo-glucanase and its combination with certain cellulases having increased stability towards anionic surfactant and/or further specific enzymes. Kao's EP 265 832 describes novel alkaline cellulase K, CMCase I and CMCase II obtained by isolation from a culture product of Bacillus sp KSM-635. Kao further describes in EP 1 350 843, alkaline cellulase which acts favourably in an alkaline environment and can be mass produced readily because of having high secretion capacity or having enhanced specific activity.
Detergent manufacturers have also attempted to incorporate bleach catalysts, especially oxaziridium or oxaziridinium-forming bleach catalysts, in their detergent products in an attempt to provide a good bleaching performance. EP 0 728 181, EP 0 728 182, EP 0 728 183, EP 0 775 192, U.S. Pat. No. 4,678,792, U.S. Pat. No. 5,045,223, U.S. Pat. No. 5,047,163, U.S. Pat. No. 5,360,568, U.S. Pat. No. 5,360,569, U.S. Pat. No. 5,370,826, U.S. Pat. No. 5,442,066, U.S. Pat. No. 5,478,357, U.S. Pat. No. 5,482,515, U.S. Pat. No. 5,550,256, U.S. Pat. No. 5,653,910, U.S. Pat. No. 5,710,116, U.S. Pat. No. 5,760,222, U.S. Pat. No. 5,785,886, U.S. Pat. No. 5,952,282, U.S. Pat. No. 6,042,744, WO95/13351, WO95/13353, WO97/10323, WO98/16614, WO00/42151, WO00/42156, WO01/16110, WO01/16263, WO01/16273, WO01/16274, WO01/16275, WO01/16276, WO01/16277 relate to detergent compositions comprising an oxaziridium and/or an oxaziridinium-forming bleach catalyst.
The inventors have found that the combination of alkaline bacterial endoglucanases with certain oxaziridinium-forming bleach catalysts leads to a surprising improvement in cleaning and whitening performance. Without wishing to be bound by theory, it is believed that the following mechanisms are likely to give rise to such benefits: the endoglucanase enzyme hydrolyses amorphous cellulose present on the cotton surface, opening up the pore structure of the fabric making it more accessible to the oxaziridinium-forming bleach chemistry. In addition, by working on yellow soils by both removal (alkaline bacterial endoglucanase) and bleaching (oxaziridinium-forming bleach), an improvement in cleaning perception is achieved. It is also believed that the combination of oxaziridinium-forming bleach chemistry with alkaline bacterial endoglucanase leads to enhanced performance of fluorescent whitening agents by the removal of soils that would otherwise inhibit the deposition and/or fluorescence yield of these materials.
The inventors have found that appropriate selection of alkaline bacterial endoglucanase and oxaziridinium-forming bleach allows to maximise the benefits and minimise negative interactions such as oxidative decomposition of the cellulase during the wash process or during storage.